This invention relates generally to a process for preparing aluminoxanes and more specifically to the preparation of aluminoxanes, such as methylaluminoxane, by reacting a hydrocarbyl aluminum compound with a hydrate of an alkali or alkaline earth metal hydroxide such as lithium hydroxide monohydrate.
Vandenberg, U.S. Pat. No. 3,219,591, reported the catalytic activity of compounds formed by the reaction of trialkyl aluminum with limited amounts of water in the polymerization of epichlorohydrin and other oxiranes. Shortly thereafter Manyik et al., U.S. Pat. No. 3,242,099, reported the use of aluminoxanes, made by reacting 0.85-1.05 moles of water with hydrocarbyl aluminum compounds such as triisobutyl aluminum, as co-catalysts with certain transition metal compounds in the polymerization of mono-unsaturated .alpha.-olefins; e.g. ethylene and propylene. Isobutylaluminoxane was also made by adding an equal mole quantity of water to a heptane solution of triisobutyl aluminum.
Manyik et al. U.S. Pat. No. 3,300,458 prepare alkylaluminoxane by passing a hydrocarbon through water to form a wet hydrocarbon and mixing the wet hydrocarbon and an alkyl aluminum/hydrocarbon solution in a conduit.
Schoenthal et al. U.S. Pat. No. 4,730,071 show the preparation of methylaluminoxane by dispersing water in toluene using an ultrasonic bath to cause the dispersion and then adding a toluene solution of trimethyl aluminum to the dispersion. Schoenthal et al. U.S. Pat. No. 4,730,072 is similar except it uses a high speed, high shear-inducing impeller to form the water dispersion.
Edwards et al. U.S. Pat. No. 4,772,736 describe an aluminoxane process in which water is introduced below the surface of solution of hydrocarbyl aluminum adjacent to a stirrer which serves to immediately disperse the water in the hydrocarbon solution.
The preparation of alkyl aluminoxanes from R.sub.2 AlOLi, formed by reacting AlR.sub.3 and anhydrous lithium hydroxide, and R.sub.2 AlCl.sub.2 has been reported in the literature, for example, Ueyama et al., Inorganic Chemistry, 12, No. 10, 2218 (1973) and Aoyazi et al., Inorganic Chemistry, 12, No. 11, 2702 (1973).
Sinn et al. U.S. Pat. No. 4,404,344 prepare methylaluminoxane by adding trimethyl aluminum to a slurry of CuSo.sub.4.5H.sub.2 O in toluene. Introducing water as a metal hydrate controls its reactivity with the trimethyl aluminum. Kaminsky et al. U.S. Pat. No. 4,544,762 is similar except it uses an aluminum sulfate salt hydrate to supply the water. Likewise, Welborn et al. U.S. 4,665,208 describe the use of other metal salt hydrates such as FeSo.sub.4.7H.sub.2 O as a water source in preparing aluminoxane. Substantial loss of aluminum values usually results when using salt hydrates (acid-base products).
I have now discovered a process for making hydrocarbylaluminoxanes using hydrates which greatly reduces the loss of aluminum values.